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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
var natives = requireNative('setIcon');
var inServiceWorker = natives.IsInServiceWorker();
// Compute a scaling factor for the image based on the supplied
// image specification.
function computeScaleFactor(imageSpec, img) {
var scaleFactor = 1;
if (imageSpec.width && imageSpec.width < img.width)
scaleFactor = imageSpec.width / img.width;
if (imageSpec.height && imageSpec.height < img.height) {
var heightScale = imageSpec.height / img.height;
if (heightScale < scaleFactor)
scaleFactor = heightScale;
}
return scaleFactor;
}
function loadImageDataForServiceWorker(imageSpec, callbacks) {
var path = imageSpec.path;
let fetchPromise = fetch(path);
let blobPromise = $Promise.then(fetchPromise, (response) => {
if (!response.ok)
throw $Error.self({ problem: 'could_not_load', path: path });
return response.blob();
});
let imagePromise = $Promise.then(blobPromise, (blob) => {
return createImageBitmap(blob);
});
let imageDataPromise = $Promise.then(imagePromise, (image) => {
if (image.width <= 0 || image.height <= 0)
throw $Error.self({ problem: 'image_size_invalid', path: path});
var scaleFactor = computeScaleFactor(imageSpec, image);
var canvas = new OffscreenCanvas(image.width * scaleFactor,
image.height * scaleFactor);
var canvasContext = canvas.getContext('2d');
canvasContext.clearRect(0, 0, canvas.width, canvas.height);
canvasContext.drawImage(image, 0, 0, canvas.width, canvas.height);
try {
var imageData = canvasContext.getImageData(
0, 0, canvas.width, canvas.height);
if (typeof callbacks.oncomplete === 'function') {
callbacks.oncomplete(
imageData.width, imageData.height, imageData.data.buffer);
}
} catch (e) {
throw $Error.self({ problem: 'data_url_unavailable', path: path });
}
});
$Promise.catch(imageDataPromise, function(error) {
if (typeof callbacks.onerror === 'function')
callbacks.onerror(error);
});
}
// This function takes an object |imageSpec| with the key |path| -
// corresponding to the internet URL to be translated - and optionally
// |width| and |height| which are the maximum dimensions to be used when
// converting the image.
function loadImageDataForNonServiceWorker(imageSpec, callbacks) {
var path = imageSpec.path;
var img = new Image();
if (typeof callbacks.onerror === 'function') {
img.onerror = function() {
callbacks.onerror({ problem: 'could_not_load', path: path });
};
}
img.onload = function() {
var canvas = document.createElement('canvas');
if (img.width <= 0 || img.height <= 0) {
callbacks.onerror({ problem: 'image_size_invalid', path: path});
return;
}
var scaleFactor = computeScaleFactor(imageSpec, img);
canvas.width = img.width * scaleFactor;
canvas.height = img.height * scaleFactor;
var canvas_context = canvas.getContext('2d');
canvas_context.clearRect(0, 0, canvas.width, canvas.height);
canvas_context.drawImage(img, 0, 0, canvas.width, canvas.height);
try {
var imageData = canvas_context.getImageData(
0, 0, canvas.width, canvas.height);
if (typeof callbacks.oncomplete === 'function') {
callbacks.oncomplete(
imageData.width, imageData.height, imageData.data.buffer);
}
} catch (e) {
if (typeof callbacks.onerror === 'function') {
callbacks.onerror({ problem: 'data_url_unavailable', path: path });
}
}
}
img.src = path;
}
function loadImageData(imageSpec, callbacks) {
if (inServiceWorker) {
loadImageDataForServiceWorker(imageSpec, callbacks);
} else {
loadImageDataForNonServiceWorker(imageSpec, callbacks);
}
}
function on_complete_index(index, err, loading, finished, callbacks) {
return function(width, height, imageData) {
delete loading[index];
finished[index] = { width: width, height: height, data: imageData };
if (err)
callbacks.onerror(index);
if ($Object.keys(loading).length == 0)
callbacks.oncomplete(finished);
}
}
function loadAllImages(imageSpecs, callbacks) {
var loading = {}, finished = [],
index, pathname;
for (var index = 0; index < imageSpecs.length; index++) {
loading[index] = imageSpecs[index];
loadImageData(imageSpecs[index], {
oncomplete: on_complete_index(index, false, loading, finished, callbacks),
onerror: on_complete_index(index, true, loading, finished, callbacks)
});
}
}
exports.$set('loadImageData', loadImageData);
exports.$set('loadAllImages', loadAllImages);
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